FDA Expands Use of Anthrax Vaccine to Include Postexposure Prevention

By Kristin J. Kelley

Edited by David G. Fairchild, MD, MPH, and Lorenzo Di Francesco, MD, FACP, FHM

The only FDA-licensed anthrax vaccine, marketed as BioThrax, is now indicated for preventing anthrax disease after confirmed or suspected exposure to the bacterium (Bacillus anthracis) that causes it.

The expanded approval was based on animal trials, says the FDA, because it wasn't possible to conduct efficacy studies in humans. The drug's safety was studied in some 200 adults, the majority of whom generated protective antibody levels similar to those seen in animal models (70% probability of survival). Common side effects are similar to those seen when the vaccine is used for pre-exposure protection, and include injection site reactions, fatigue, headaches, and muscle aches.